Semiconductor device and method of manufacturing same

Abstract

To provide a semiconductor device and a method of manufacturing the same capable of suppressing, when a plurality of MIS transistors having different absolute values of threshold voltage is used, the reduction of the drive current of a MIS transistor having a greater absolute value of threshold voltage. The threshold voltage of a second nMIS transistor is greater than the threshold voltage of a first nMIS transistor and the sum of the concentration of lanthanum atom and the concentration of magnesium atom in a second nMIS high-k film included in the second nMIS transistor is lower than the sum of the concentration of lanthanum atom and the concentration of magnesium atom in a first nMIS high-k film included in the first nMIS transistor.

What is claimed is: 
     
       1. A method of manufacturing a semiconductor device comprising the steps of:
 forming a first and a second nMIS channel region having a p-type conductive type by injecting p-type impurities onto a semiconductor substrate; 
 forming a high-k film over the first and second nMIS channel regions; 
 forming an nMIS cap film containing at least either of lanthanum and magnesium so as to cover the part over the first nMIS channel region of the high-k film and to expose the part over the second nMIS channel region of the high-k film; 
 forming a first nMIS metal electrode over the first nMIS channel region via the high-k film and the nMIS cap film and forming a second nMIS metal electrode over the second nMIS channel region via the high-k film; and 
 diffusing at least either of lanthanum and magnesium contained in the nMIS cap film into the part over the first nMIS channel region of the high-k film, 
 wherein the absolute value of the second nMIS threshold voltage is greater than the absolute value of the first nMIS threshold voltage, and 
 wherein the sum of the concentration of lanthanum atom and the concentration of magnesium atom in the second nMIS high-k film is lower than the sum of the concentration of lanthanum atom and the concentration of magnesium atom in the first nMIS high-k film. 
 
     
     
       2. The method of manufacturing a semiconductor device according to  claim 1 , wherein the first and second nMIS metal electrodes are made of one material. 
     
     
       3. The method of manufacturing a semiconductor device according to  claim 1 ,
 wherein the step of forming the first and second nMIS channel regions is performed by simultaneously forming each of the first and second nMIS channel regions. 
 
     
     
       4. A method of manufacturing a semiconductor device comprising the steps of:
 forming a first and a second pMIS channel region having an n-type conductive type by injecting n-type impurities onto a semiconductor substrate; 
 forming a high-k film over the first and second pMIS channel regions; 
 forming a pMIS cap film containing aluminum so as to cover the part over the first pMIS channel region of the high-k film and to expose the part over the second pMIS channel region of the high-k film; 
 forming a first pMIS metal electrode over the first pMIS channel region via the high-k film and the pMIS cap film and forming a second pMIS metal electrode over the second pMIS channel region via the high-k film; and 
 diffusing aluminum contained in the pMIS cap film into the part over the first pMIS channel region of the high-k film, 
 wherein the absolute value of the second pMIS threshold voltage is greater than the absolute value of the first pMIS threshold voltage, and 
 wherein the concentration of aluminum atom in the second pMIS high-k film is lower than the concentration of aluminum atom in the first pMIS high-k film. 
 
     
     
       5. The method of manufacturing a semiconductor device according to  claim 4 ,
 wherein the first and second pMIS metal electrodes are made of one material. 
 
     
     
       6. The method of manufacturing a semiconductor device according to  claim 4 ,
 wherein the step of forming the first and second pMIS channel regions is performed by simultaneously forming each of the first and second pMIS channel regions.